Anathem

I commented at the strangelove4sf blog on Anathem by Neal Stephenson (William Morrow, 2008).
This must be one of the most compelling science fictional treatments of a cloistered community since Walter M. Miller's A Canticle for Liebowitz (1960), and is the most ambitious fictional treatment of the history of ideas that I recall. Its theme is fairly abstract, and will appeal most to readers who find something intriguing and immediate in this question:
   What of praxis if epistemology is ontology?